But (i32 length, byte[] data) is as complex as (byte[] data, '\0'), its two-parts anyway. Of course it allows potentially for very long strings at the cost of just a single byte spent as a terminator. Beside the rarity of such a case, the "space savings" might play a role on a PDP11, or on a Z80, but not on any of the modern architectures that need structures aligned to 32 or even 64 bit boundary. The efficiency and security costs far outweigh any savings is space or simplicity (heh) of processing.

Null-terminated strings are the other billion-dollar mistake, along with the original NULL.